SCPT-Based Monotonic Soil Reaction Model for Monopiles in Sand: Calibration with Centrifuge Tests and Assessment against Field Data

Abstract This paper presents a soil reaction framework for monotonic lateral analysis of offshore wind monopiles in sand, formulated using input parameters that can be derived from seismic cone penetration test (SCPT) data. The model adopts a multicomponent Winkler representation incorporating distributed lateral, distributed moment, and base shear reactions within a unified bounding-surface plasticity formulation. This approach enables direct linkage between soil reaction behavior and site-specific soil properties, namely small-strain stiffness and cone penetration resistance inferred from in situ measurements. Model calibration is supported by an original centrifuge testing program conducted within the Monopile Improved Design through Advanced Cyclic Soil Modeling (MIDAS) project, covering monopile geometries and sand densities representative of offshore wind applications. The calibrated parameter ranges are subsequently evaluated against independent field test data sets from the Pile Soil Analysis (PISA) and VIBRO research programs. Comparisons indicated that the proposed formulation reproduces global load-displacement response and bending moment distributions with satisfactory accuracy across a range of pile–soil relative stiffness conditions. The proposed framework provides a computationally efficient alternative to three-dimensional finite-element analyses for monopile design, particularly during early wind farm development stages when high-fidelity simulations are constrained by time and/or limited soil data.